Prior to 1945 the Defence Ministry was titled the Secretariat of War (Secretaría de la Guerra).

An agreement signed in September 1996, which is one of the substantive peace accords, mandated that the mission of the armed forces change to focus exclusively on external threats.[2] Presidents Álvaro Arzú and his successors Alfonso Portillo, Óscar Berger and Álvaro Colom, have used a constitutional clause to order the army on a temporary basis to support the police in response to a nationwide wave of violent crime, a product of the Mexican criminal organizations going across the north-west region.

The peace accords call for a one-third reduction in the army's authorized strength and budget — achieved in 2004 — and for a constitutional amendment to permit the appointment of a civilian minister of defense. A constitutional amendment to this end was defeated as part of a May 1999 plebiscite, but discussions between the executive and legislative branches continue on how to achieve this objective.

In 2004 the army has gone beyond its accord-mandated target, and has implemented troop reductions from an estimated 28,000 to 15,500 troops,[3] including subordinate air force (1,000) and navy (1,000) elements. It is equipped with armaments and material from the United States, Israel, Taiwan, Argentina, Spain, and France. As part of the army downsizing, the operational structure of 19 military zones and three strategic brigades are being recast as several military zones are eliminated and their area of operations absorbed by others. The air force operates three air bases; the navy has two port bases.[4]

The Guatemalan army has a special forces unit (specializing in anti-insurgent jungle warfare) known as the Kaibiles. In 2011, a Guatemalan court convicted four members of the Kaibiles, of killing more than 200 civilians in the Dos Erres massacre in 1982.[5] Each man was sentenced to 6,050 years in prison. Their convictions for their roles in the massacre nearly 30 years prior, in which soldiers killed more than 200 men, women, and children, would not have happened if not for the courage of victims of violence and Guatemala’s attorney general, Claudia Paz y Paz. After the convictions of the Dos Erres four, based on a Guatemalan government’s commitment to reorganize its special forces units, the U.S. Department of Defense resumed military aid.